An ecological framework for contextualizing carnivore–livestock conflict

Carnivore predation on livestock is a complex management and policy challenge, yet it is also intrinsically an ecological interaction between predators and prey. Human–wildlife interactions occur in socioecological systems in which human and environmental processes are closely linked. However, underlying human–wildlife conflict and key to unpacking its complexity are concrete and identifiable ecological mechanisms that lead to predation events. To better understand how ecological theory accords with interactions between wild predators and domestic prey, we developed a framework to describe ecological drivers of predation on livestock. We based this framework on foundational ecological theory and current research on interactions between predators and domestic prey. We used this framework to examine ecological mechanisms (e.g., density-mediated effects, behaviorally mediated effects, and optimal foraging theory) through which specific management interventions operate, and we analyzed the ecological determinants of failure and success of management interventions in 3 case studies: snow leopards (Panthera uncia), wolves (Canis lupus), and cougars (Puma concolor). The varied, context-dependent successes and failures of the management interventions in these case studies demonstrated the utility of using an ecological framework to ground research and management of carnivore–livestock conflict. Mitigation of human–wildlife conflict appears to require an understanding of how fundamental ecological theories work within domestic predator–prey systems.     

Heavy metals in seaducks and mussels from misty fjords national monument in Southeast Alaska

Quartz Hill, in Misty Fjords National Monument near Ketchikan, Alaska, is the site of a proposed molybdenum-producing mine. To provide baseline data for use in post-development comparisons, we analyzed tissues of Barrow's goldeneyes (Bucephala islandica), common mergansers (Mergus merganser), and blue mussels (Mytilus edulis) for seven heavy metals that could potentially be released into the environment as a result of mining operations. Specimens were collected in 1980, 1981, and 1982 from two fjords likely to be used for discharge of tailings from the proposed mine and from two control fjords. Concentrations of arsenic, cadmium, copper, chromium, molybdenum, lead, and zinc were measured in soft tissues of mussels and in kidney, liver, and muscle of birds. The highest mean concentrations of metals found in bird tissues were 55.7 ppm dry weight cadmium in kidneys and 154 ppm dry weight zinc in livers of Barrow's goldeneyes. Concentrations of several metals in blue mussels differed among seasons and locations, but the most significant finding in mussels was a maximum mean cadmium concentration of 9.6 ppm dry weight, a level higher than normally found in undisturbed areas. With the exception of 104 ppm dry weight cadmium in the kidney of one common merganser and 12.7 ppm dry weight lead in the kidney of another, concentrations of other metals in seaduck and mussel tissues were low, consistent with what would be expected for a pre-development environment. Molybdenum was found in low concentrations (<10 ppm dry weight) in all avian kidney samples and most liver samples, but was not detected in blue mussels.THE U.S. GOVERNMENT RIGHT TO RETAIN A NON-EXCLUSIVE, ROYALTY FREE LICENCE IN AND TO ANY COPYRIGHT IS ACKNOWLEDGED.     

Cross-boundary management between national parks and surrounding lands: A review and discussion

Protecting biodiversity on public lands is difficult, requiring the management of a complex array of factors. This is especially true when the ecosystems in question are affected by, or extend onto, lands outside the boundaries of the protected area. In this article we review recent developments in the cross-boundary management of protected natural resources, such as parks, wildlife reserves, and designated wilderness areas. Five ecological and 11 anthropic techniques have been suggested for use in cross-boundary management. The categories are not mutually exclusive, but each is a distinct and representative approach, suggested by various authors from academic, managerial, and legal professions. The ecological strategies stress the collection of basic data and documentation of trends. The anthropic techniques stress the usefulness of cooperative guidelines and the need to develop a local constituency which supports park goals. However, the situation is complex and the needed strategies are often difficult to implement. Diverse park resources are influenced by events in surrounding lands. The complexity and variability of sources, the ecological systems under protection, and the uncertainty of the effects combine to produce situations for which there are no simple answers. The solution to coexistence of the park and surrounding land depends upon creative techniques and recommendations, many still forthcoming. Ecological, sociological, legal, and economic disciplines as well as the managing agency should all contribute to these recommendations. Platforms for change include legislation, institutional policies, communication, education, management techniques, and ethics.     

Intercontinental chemical variation in the invasive ant Wasmannia auropunctata (Roger) (Hymenoptera Formicidae): a key to the invasive success of a tramp species

Unicoloniality emerges as a feature that characterizes successful invasive species. Its underlying mechanism is reduced intraspecific aggression while keeping interspecific competitiveness. To that effect, we present here a comparative behavioural and chemical study of the invasive ant Wasmannia auropunctata in parts of its native and introduced ranges. We tested the hypothesis that introduced populations (New Caledonia archipelago) have reduced intraspecific aggression relative to native populations (e.g., Ilhéus area, Brazil) and that this correlates with reduced variability in cuticular hydrocarbons (CHCs). As predicted, there was high intraspecific aggression in the Brazilian populations, but no intraspecific aggression among the New Caledonian populations. However, New Caledonian worker W. auropunctata remained highly aggressive towards ants of other invasive species. The chemical data corresponded with the behaviour. While CHCs of ants from the regions of Brazil diverged, the profiles of ants from various localities in New Caledonia showed high uniformity. We suggest that in New Caledonia W. auropunctata appears to behave as a single supercolony, whereas in its native range it acts as a multicolonial species. The uniformity of recognition cues in the New Caledonia ants may reflect a process whereby recognition alleles became fixed in the population, but may also be the consequence of a single introduction event and subsequent aggressive invasion of the ecosystem. Chemical uniformity coupled with low intraspecific but high interspecific aggression, lend credence to the latter hypothesis.     

Reactions of cloned poplars to air pollution

Ozone-induced changes in ethylene production, ACC oxidase activity and the contents of ACC, MACC and free PAs were studied inPopulus nigra L. cv. Loenen with high ozone sensitivity as judged by the degree of chlorophyll degradation and premature leaf abscission. Ethylene production, ACC oxidase activity, ACC content and MACC levels were induced by the one-, two-, and three-week ozone exposure (36±9 ppb O₃ for 11 hours a day). In addition, increases in PA levels, especially in spermidine, were measured in ozone treated plants. The role of free PAs and MACC synthesis as possible antisenescence reactions is discussed.     

Interactive effects of prey and p,p'-DDE on burrowing owl population dynamics.

We used population models to explore the effects of the organochlorine contaminant p,p'-DDE and fluctuations in vole availability on the population dynamics of Burrowing Owls (Athene cunicularia). Previous work indicated an interaction between low biomass of voles in the diet and moderate levels of p,p'-DDE in Burrowing Owl eggs that led to reproductive impairment. We constructed periodic and stochastic matrix models that incorporated three vole population states observed in the field: average, peak, and crash years. We modeled varying frequencies of vole crash years and a range of impairment of owl demographic rates in vole crash years. Vole availability had a greater impact on owl population growth rate than did reproductive impairment if vole populations peaked and crashed frequently. However, this difference disappeared as the frequency of vole crash years declined to once per decade. Fecundity, the demographic rate most affected by p,p'-DDE, had less impact on population growth rate than adult or juvenile survival. A life table response experiment of time-invariant matrices for average, peak, and crash vole conditions showed that low population growth under vole crash conditions was due to low adult and juvenile survival rates, whereas the extremely high population growth under vole peak conditions was due to increased fecundity. Our results suggest that even simple models can provide useful insights into complex ecological interactions. This is particularly valuable when temporal or spatial scales preclude manipulative experimental work in the field or laboratory.     

Colonial recognition of fungus in the fungus-growing ant Acromyrmex subterraneus subterraneus (Hymenoptera: Formicidae)

Summary. Leaf cutting ants live in symbiosis with a basidiomycete fungus that is exploited as a source of nutrients for the ant larvae. Tests of fungus transport demonstrated that Acromyrmex subterraneus subterraneus workers discriminate concolonial fungus from alien fungus, and rejected the latter. Larvae and pupae of the ant were used as controls. Chemical analysis of the fungus revealed a great similarity between its hydrocarbon profile and that found on the ant brood. Experiments with lures showed that chemical extracts from the fungus are responsible for this discrimination process. Moreover, the presence of brood inside the fungus seemed to be important for discrimination of the fungus by workers. Resident workers accepted concolonial broodless fungus less than concolonial fungus inoculated with brood odor. Fungus seems to acquire colonial odor passively, simply by contact with the brood. The impact of fungus volume present in the nest on closure of the colony is discussed. We show here for the first time the importance of a symbiotic vegetal organism in colonial recognition in social insects. Received 14 April 2000; accepted 29 September 2000